Question

What is the sequence of different phases in the cell cycle?

Answer 1

Cell cycle consists of the events by which a cell synthesizes and duplicates its genome and other components, and eventually divides into two daughter cells. The cell cycle consists of two phases- one where the cell prepares itself for cell division and second where the cell divides.

Complete answer:
Cell division is defined as a process in which a single parent cell is divided into two daughter cells. The cell cycle is a genetically controlled series of changes that occur in a newly formed cell by which it duplicates its contents, undergoes growth and division to form two daughter cells.
The cell cycle consists of two phases:
-Interphase: Interphase is a phase between two successive M phases, where the cell prepares itself for cell division. It constitutes more than 95% of the cell cycle.
-M phase or Mitotic Phase: Mitosis or M phase is the phase where the actual cell division occurs. In this phase, the cell utilizes the constituents formed during the interphase and divides into two daughter cells.
The sequence of the cell cycle is:
Interphase:
-${ G }_{ 1 }$ Phase
-S-phase
-${ G }_{ 2 }$ Phase
Mitosis phase:
Karyokinesis: Division of the nucleus
-Prophase
-Metaphase
-Anaphase
-Telophase
Cytokinesis: Division of cytoplasm

Additional Information: Interphase:
It is a long, non-dividing growing phase of the cell cycle, where the cell prepares itself for the division. It represents the most active stage of the cell cycle.
It is further divided into three stages:
${ G }_{ 1 }$ Phase: It is the interval between mitosis and initiation of DNA replication. In this phase, the cell grows in size continuously and synthesizes nucleotides, ATP, amino acids, RNA, etc. Most of the organelles duplicate in this phase.
${ G }_{ 0 }$ Phase: The non-dividing cell enters the quiescent stage of the cell cycle. In this phase, the cell remains metabolically active but does not proliferate unless they are called on to do so.
S- Phase: it is also known as the synthesis phase. It is a phase in which synthesis or replication of DNA takes place and there is a doubling of DNA. For example, if the DNA is 2N, then after the S phase the DNA becomes 4N. During this phase, DNA replication starts in the nucleus while the centrioles duplicate in the cytoplasm.
${ G }_{ 2 }$ Phase: It is the second gap phase present between S and M phases.
M phase or mitotic phase is the phase where actual cell division occurs. It consists of 2 processes, karyokinesis, and cytokinesis.
-Karyokinesis: Here division of the nucleus occurs in 4 stages.
Prophase: Condensation of chromatin material takes place and DNA strands untangle to form compact mitotic chromosomes. Each chromosome appears double and consists of two chromatids joined by a centromere.
Metaphase: In this phase, the disintegration of the nuclear envelope occurs and chromosomes spread throughout the cytoplasm. Mitotic spindle formation is complete. All the chromosomes align themselves at the equator, along the metaphase plate. The microtubules of spindle fibres attach to the kinetochores.
Anaphase: In this phase, the centromere splits and separated daughter chromatids migrate to the opposite poles.
Telophase: The chromosomes reach their respective poles. The mitotic spindle disappears. The chromosomes gradually uncoil and become thin and lose their identity. All other organelles reappear.
-Cytokinesis: This phase marks the end of the cell division. The division of cytoplasm occurs in this phase. Cytokinesis is achieved by the formation of a furrow in the plasma membrane. It deepens and ultimately divides the cell cytoplasm into two.

Note: -Interphase is a biosynthetic phase in which the cell duplicates its organelles and replicates its DNA.
-Period of the cell cycle varies from organism to organism and also from cell to cell.
-Interphase is also called the Resting phase because it does not involve any activity related to cell division.
-Some cells in adult animals do not divide e.g., nerve cells.
-In the S phase, the DNA doubles but the chromosomes remain the same.